HARLEY DAVIDSON motorcycle owners are loyal and enthusiastic about their motorcycles. Owners of HARLEY DAVIDSON motorcycles are generally not reluctant to modify, customize or improve their motorcycles. Aftermarket parts and kits to modify HARLEY DAVIDSON motorcycles are popular.
The traditional HARLEY DAVIDSON drivetrain includes a V-TWIN engine positioned forward the transmission in which both the engine and transmission are independently secured or bolted together and secured to the motorcycle frame. In particular, HARLEY DAVIDSON V-TWIN engine motorcycles incorporate separate cases for the engine and the transmission.
In one well-known configuration, the drivetrain assembly comprises a leftside drive in which the engine includes a crankshaft and output shaft substantially parallel to an input shaft of the transmission. Engine power is coupled to the transmission with a primary belt or chain interconnecting the parallel output and inputs shafts of the engine and transmission respectively. The drive assembly additionally includes a primary drive housing on the leftside of the motorcycle for enclosing the primary belt or chain interconnecting the parallel output and input shafts. The transmission includes an output shaft on the left side that connects by a chain to the rear wheel drive sprocket.
The present inventors have recognized that as riders of motorcycles age, the strength and coordination required to clutch and shift a four or five-speed motorcycle transmission using coordinated movement of arms and legs, can be problematic. The coordinated movements can become too physically taxing for older riders.
The present inventors have recognized the desirability of providing motorcycles, particularly HARLEY DAVIDSON and like motorcycles with a compact and effective automatic transmission arrangement that can make the motorcycle more easily operated by older riders or physically impaired riders.
The present inventors have recognized that the HARLEY DAVIDSON V-TWIN engine motorcycle is a likely candidate for a transmission modification to accommodate an automatic transmission given the separate casings for the engine and transmission on these motorcycles.
There have been attempts to provide a motorcycle with an automatic transmission. Such attempts include those disclosed in U.S. Pat. Nos. 6,390,262; 4,702,340; 5,951,434; 6910,987 and 5,862,717. Some of the embodiments described in these patents however suffer the drawbacks of providing an automatic transmission that is overly complex, bulky, or not adaptable to be easily installed on a HARLEY DAVIDSON motorcycle.
The present inventors have recognized that it would be beneficial if commercially available automobile transmissions could be easily adapted for use on motorcycles.
The present inventors have recognized one problem with utilizing a more readily available automobile automatic transmission on a motorcycle is that a conventional automobile automatic transmission input shaft is designed to rotate clockwise, when viewed looking into an end of the input shaft. Because of its side ways orientation, a conventional motorcycle engine is designed to rotate counterclockwise when viewed looking into an end of the output shaft. Thus, if a conventional automatic transmission is arranged on a motorcycle having its input shaft parallel to the engine output shaft and on the same side of the motorcycle, the two shafts cannot be coupled easily with a chain or belt because of their opposite rotational directions.